The present invention relates to a light-emitting fiber and, in particular, to a long light-emitting fiber and a method for making same.
It has long been desired that electronic displays be made with larger screen sizes and also be very thin, ultimately reaching a configuration that may be hung on a wall. Inherent physical limitations preclude conventional cathode ray tubes, such as the color picture tubes and display tubes utilized in televisions, computer displays, monitors and the like, from achieving such desired result. While plasma displays have been proposed to satisfy such desire, the large glass vacuum envelope they require is difficult to manufacture, and thus is expensive, which is not desirable.
The entire display screen of such plasma devices must be fabricated as a single piece and must reproduce many thousands of pixels. Any significant defect that results in faulty pixels or in a non-uniform brightness across the screen, even if confined to a relatively small area, renders the entire screen defective. Such defects cannot be tested or detected until the entire screen is processed, and are either not susceptible of repair or are very expensive to repair, thereby substantially reducing the yield and increasing the cost of each satisfactory plasma display.
One attractive approach for producing a large, thin display screen is to provide an array of a large number of adjacent light-emitting fibers. An advantage of such light-emitting fiber display is that each fiber is relatively inexpensive and may be separately tested before assembly into a display. Because defective fibers are detected and discarded before assembly into a display, the yield of a display which is made from known good light-emitting fibers is increased and the cost thereof is reduced. One such fiber display is described in U.S. Pat. No. 6,274,978 entitled xe2x80x9cFIBER-BASED FLAT PANEL DISPLAYxe2x80x9d (U.S. patent application Ser. No. 09/418,454 filed Oct. 15, 1999).
With regard to such fiber-based displays, it is desirable that light-emitting fibers therefor be available that can be fabricated in a variety of ways, such as for improving performance, enhancing processing, enabling testing, facilitating assembly of fibers into a display, and/or reducing cost.
Accordingly, there is a need for a light-emitting fiber that is fabricated in a way that tends to improve the useful life of the light-emitting elements and/or to facilitate assembly of fibers into a display.
To this end, the light-emitting fiber of the present invention comprises a length of a fiber of an optically transparent material, a first electrode including a plurality of electrode segments disposed along the length of a first surface of the fiber, wherein said electrode segments include a layer of an optically-transparent electrically conductive material, and an elongated electrical conductor disposed along the length of the fiber on a second surface thereof that is contiguous to the first surface thereof, wherein the elongated electrical conductor is in electrical contact with each of the electrode segments along the length of the fiber. A light-emitting material is disposed on the plurality of electrode segments, and a plurality of electrical contacts are disposed in one-to-one relation to the electrode segments on the light-emitting material along the length of the fiber, wherein the light-emitting material disposed between a given one of the electrode segments and a corresponding one of the electrical contacts emits light responsive to an electrical signal applied between the elongated electrical conductor and the corresponding one electrical contact.
According to another aspect of the invention, a method for making a light-emitting fiber having a plurality of light-emitting elements thereon comprises:
providing a length of optical fiber;
depositing a plurality of spaced-apart first electrode segments along the length of optical fiber;
depositing an electrical conductor along a side of the length of optical fiber and in electrical contact with the plurality of spaced-apart first electrode segments;
depositing a layer of a light-emitting material on the first electrode segments along the optical fiber; and
depositing a plurality of electrical contacts on the light-emitting material and extending to overlie spaces between adjacent ones of the spaced-apart first electrode segments.